Skeletal muscle mass and all-cause mortality: Findings from the CRONICAS cohort study.

OBJECTIVE: We aimed (1) to evaluate the agreement between two methods (equation and bio-impedance analysis [BIA]) to estimate skeletal muscle mass (SMM), and (2) to assess if SMM was associated with all-cause mortality risk in individuals across different geographical sites in Peru. METHODS: We used data from the CRONICAS Cohort Study (2010-2018), a population-based longitudinal study in Peru to assess cardiopulmonary risk factors from different geographical settings. SMM was computed as a function of weight, height, sex and age (Lee equation) and by BIA. All-cause mortality was retrieved from national vital records. Cox proportional-hazard models were developed and results presented as hazard ratios (HRs) with 95% confidence intervals (95% CIs). RESULTS: At baseline, 3216 subjects, 51.5% women, mean age 55.7 years, were analysed. The mean SMM was 23.1 kg (standard deviation [SD]: 6.0) by Lee equation, and 22.7 (SD: 5.6) by BIA. Correlation between SMM estimations was strong (Pearson's ρ coefficient = 0.89, p < 0.001); whereas Bland-Altman analysis showed a small mean difference. Mean follow-up was 7.0 (SD: 1.0) years, and there were 172 deaths. In the multivariable model, each additional kg in SMM was associated with a 19% reduction in mortality risk (HR = 0.81; 95% CI: 0.75-0.88) using the Lee equation, but such estimate was not significant when using BIA (HR = 0.98; 95% CI: 0.94-1.03). Compared to the lowest tertile, subjects at the highest SMM tertile had a 56% reduction in risk of mortality using the Lee equation, but there was no such association when using BIA estimations. CONCLUSION: There is a strong correlation and agreement between SMM estimates obtained by the Lee equation and BIA. However, an association between SMM and all-cause mortality exists only when the Lee equation is used. Our findings call for appropriate use of approaches to estimate SMM, and there should be a focus on muscle mass in promoting healthier ageing.

Dielectric Dispersion Modulated Sensing of Yeast Suspension Electroporation.

A specific pulsed electric field protocol can be used to induce electroporation. This is used in the food industry for yeast pasteurization, in laboratories for generic transfer and the medical field for cancer treatment. The sensing of electroporation can be done with simple 'instantaneous' voltage-current analysis. However, there are some intrinsic low-frequency phenomena superposing the electroporation current, such as electrode polarization. The biological media are non-homogeneous, giving them specific characterization in the broad frequency spectrum. For example, the cell barrier, i.e., cell membrane, causes so called ß-dispersion in the frequency range of tens to thousands of kHz. Electroporation is a dynamic phenomenon characterized by altering the cell membrane permeability. In this work, we show that the impedance measurement at certain frequencies could be used to detect the occurrence of electroporation, i.e., dielectric dispersion modulated sensing. This approach may be used for the design and implementation of electroporation systems. Yeast suspension electroporation is simulated to show changes in the frequency spectrum. Moreover, the alteration depends on characteristics of the system. Three types of external buffers and their characteristics are evaluated.

Determinación del estado nutricional mediante el ángulo de fase en pacientes en hemodiálisis.

INTRODUCTION: Multi-frequency bio-impedance analysis (BIA) accurately evaluates body composition. OBJECTIVE: To assess nutritional status and its relationship with body mass index (BMI) or with BIA-obtained phase angle in patients with end-stage renal disease (ESRD) on hemodialysis. METHOD: BMI, BIA and dialysis malnutrition score (DMS) were assessed in 99 patients on hemodialysis (43.6 ± 17.2 years of age, 58.8% males). Multivariate linear regression analysis was used to determine BMI and phase angle independent associations with DMS. RESULTS: Malnutrition risk (DMS > 13) showed a gradual increase among patients with normal BMI and phase angle (44.4%), low BMI (45.8%), low phase angle (64.0%), and in those with both parameters at abnormal ranges (68.0%). The phase angle was the only variable that was independently associated with patient nutritional status (standardized coefficient beta -0.372, p < 0.001), accounting for 13.8% of DMS variation. CONCLUSION: Phase angle is inversely and independently associated with malnutrition risk in patients with ESRD, which suggests that BIA-assessed body composition might be better than BMI in the clinical assessment of patients with ESRD.

INTRODUCCIÓN: La bioimpedancia eléctrica multifrecuencia (BIE) evalúa con precisión la composición corporal. OBJETIVO: Investigar el estado nutricional y su relación con el índice de masa corporal (IMC) o el ángulo fase obtenido por BIE en pacientes con enfermedad renal terminal (ERT) en hemodiálisis. MÉTODO: En 99 pacientes en hemodiálisis (43.6 ± 17.2 años, 58.8 % varones) se evaluó IMC, BIE y puntuación de desnutrición (DMS, Dialysis Malnutrition Score). La independencia de las asociaciones del IMC y el ángulo fase con el DMS se determinó con regresión lineal múltiple. RESULTADOS: El riesgo de desnutrición (DMS > 13) se incrementó gradualmente entre los sujetos con IMC y ángulo fase normales (44.4 %), IMC bajo (45.8 %), ángulo fase bajo (64.0 %) y en aquellos con ambos parámetros anormales (68.0 %). El ángulo fase fue la única variable asociada independientemente con el estado nutricional de los pacientes (coeficiente beta estandarizado −0.372, p < 0.001), lo que explicó 13.8 % de la variación en el DMS. CONCLUSIONES: El ángulo fase se asocia inversa e independientemente con el riesgo de desnutrición en pacientes con ERT, lo que sugiere que la composición corporal evaluada por BIE pudiera ser mejor que el IMC en la valoración clínica de pacientes con esta enfermedad.

Determinación del estado nutricional mediante el ángulo de fase en pacientes en hemodiálisis / Determination of nutritional status by phase angle in hemodialysis patients

Resumen Introducción: La bioimpedancia eléctrica multifrecuencia (BIE) evalúa con precisión la composición corporal. Objetivo: Investigar el estado nutricional y su relación con el índice de masa corporal (IMC) o el ángulo fase obtenido por BIE en pacientes con enfermedad renal terminal (ERT) en hemodiálisis. Método: En 99 pacientes en hemodiálisis (43.6 ± 17.2 años, 58.8 % varones) se evaluó IMC, BIE y puntuación de desnutrición (DMS, Dialysis Malnutrition Score). La independencia de las asociaciones del IMC y el ángulo fase con el DMS se determinó con regresión lineal múltiple. Resultados: El riesgo de desnutrición (DMS > 13) se incrementó gradualmente entre los sujetos con IMC y ángulo fase normales (44.4 %), IMC bajo (45.8 %), ángulo fase bajo (64.0 %) y en aquellos con ambos parámetros anormales (68.0 %). El ángulo fase fue la única variable asociada independientemente con el estado nutricional de los pacientes (coeficiente beta estandarizado −0.372, p < 0.001), lo que explicó 13.8 % de la variación en el DMS. Conclusiones: El ángulo fase se asocia inversa e independientemente con el riesgo de desnutrición en pacientes con ERT, lo que sugiere que la composición corporal evaluada por BIE pudiera ser mejor que el IMC en la valoración clínica de pacientes con esta enfermedad.

Abstract Introduction: Multi-frequency bio-impedance analysis (BIA) accurately evaluates body composition. Objective: To assess nutritional status and its relationship with body mass index (BMI) or with BIA-obtained phase angle in patients with end-stage renal disease (ESRD) on hemodialysis. Method: BMI, BIA and dialysis malnutrition score (DMS) were assessed in 99 patients on hemodialysis (43.6 ± 17.2 years of age, 58.8% males). Multivariate linear regression analysis was used to determine BMI and phase angle independent associations with DMS. Results: Malnutrition risk (DMS > 13) showed a gradual increase among patients with normal BMI and phase angle (44.4%), low BMI (45.8%), low phase angle (64.0%), and in those with both parameters at abnormal ranges (68.0%). The phase angle was the only variable that was independently associated with patient nutritional status (standardized coefficient beta −0.372, p < 0.001), accounting for 13.8% of DMS variation. Conclusion: Phase angle is inversely and independently associated with malnutrition risk in patients with ESRD, which suggests that BIA-assessed body composition might be better than BMI in the clinical assessment of patients with ESRD.

Does the speed of aquatic therapy exercise alter arm volume in women with breast cancer related lymphoedema? A cross-over randomized controlled trial.

OBJECTIVE: To identify whether slow aquatic exercise in the form of modified Ai Chi is more effective than conventional (faster pace) aquatic therapy at reducing arm volume in women with or at risk of breast cancer related lymphoedema. METHODS: Randomized, cross-over controlled trial with concealed allocation and blinded assessment. Eighteen women with a history of breast cancer related lymphoedema were recruited. Participants received two intervention sessions (randomized order) with one week apart. Interventions were a 50min conventional aquatic intervention or a 50min modified Ai Chi. Arm volume was measured as the difference between affected and unaffected arm; bio-impedance was measured as an index of extracellular fluid; satisfaction was measured via a 12 question form. Outcomes were measured before, immediately after and one hour after intervention. RESULTS: Comparison between interventions showed larger decreased arm volume of 140mL (95%CI 17-263) immediately after intervention in favor of the Ai Chi intervention, however it was not sustained at 1h follow-up. A post hoc analysis showed 72% of participants had a decrease in arm volume immediately after Ai Chi compared to 28% immediately after conventional aquatic therapy; with a number needed to treat of 3 (95%CI 1.4-6.6). There were no differences between interventions for bio-impedance. Satisfaction was good for both interventions. CONCLUSION: Slow pace aquatic exercise is more effective than conventional aquatic exercise immediately after intervention for arm volume. Also, undesirable increase in arm volume seems to subside after 1h, which can be beneficial if therapy does not address arm volume. TRIAL REGISTRATION: ACTRN12614000557639 (https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?ACTRN=12614000557639).

Effect of psychological stress on gastric motility assessed by electrical bio-impedance.

AIM: To evaluate gastric motility using electrical bio-impedance (EBI) and gastric changes as a result of stress induced by psychological tests. METHODS: A group of 57 healthy women, aged 40-60 years, was recruited, and a clinical history and physical examination were performed. The women were free from severe anxiety, chronic or acute stress, severe depression, mental diseases and conditions that affect gastric activity. The women were evaluated under fasting conditions, and using a four-electrode configuration, the gastric signals were obtained through a BIOPAC MP-150 system. The volunteers were evaluated using the following paradigm: basal state, recording during the Stroop Test, intermediate resting period, recording during the Raven Test, and a final resting period. We analyzed the relative areas of the frequency spectrum: A1 (1-2 cpm), A2 (2-4 cpm), A3 (4-8 cpm), and A4 (8-12 cpm), as well as the median of area A2 + A3. The data were analyzed by an autoregressive method using a Butterworth filter with MatLab and Origin. Analysis of variance (ANOVA) and Friedman ANOVA (for nonparametric variables) were performed; in addition, pairs of groups were compared using the T dependent and Wilcoxon T tests. RESULTS: The results of the main values of area A2 were not significantly different comparing the five steps of the experimental paradigm. Nevertheless, there was a tendency of this A2 region to decrease during the stress tests, with recuperation at the final resting step. When an extended gastric region was considered (1-4 cpm), significant differences with the psychological stress tests were present (F = 3.85, P = 0.005). The A3 region also showed significant changes when the stress psychological tests were administered (F = 7.25, P < 0.001). These differences were influenced by the changes in the adjacent gastric region of A2. The parameter that we proposed in previous studies for the evaluation of gastric motility by electrical bio-impedance (EBI) was the median of the area under the region from 2 to 8 cpm (A2 + A3). The mean values of these frequencies (median of the A2 + A3 area) with the stress test showed significant changes (F = 5.5, P < 0.001). The results of the Wilcoxon T test for the A4 area parameter, which is influenced by the breathing response, changed significantly during the Raven stress test (P < 0.05). CONCLUSION: We confirm that the gastric response to acute psychological stress can be evaluated by short-term EBI.

Avaliação da hidratação dos alunos do curso de formação de Pára-quedistas Militares do Exército Brasileiro / Assessment of hydration among Brazilian army parachuting training program rookies

Este estudo teve como objetivo avaliar a hidratação dos alunos do Curso Básico Páraquedista (C Bas Pqdt - Curso de Formação dos Pára-quedistas Militares Brasileiros) de acordo com a variação da massa corporal e do calculo do total de líquidos corporais a partir do método de bioimpedância elétrica. A coleta de dados ocorreu durante as três semanas da 1ª fase do Curso Básico Pára-quedista, de 7 a 25 de janeiro de 2008. A amostra foi selecionada de forma aleatória entre os 422 alunos que iniciaram o curso. Participaram do estudo 90 militares do sexo masculino, voluntários, que podem ser caracterizados pelos seguintes dados antropométricos médios: idade(25,08 ± 3,96 anos); peso (76,53 ± 7,39 kg); altura (174,53 ± 5,85 cm) e percentual de gordura (14,07 ± 4,09). A perda hídrica percentual média foi de 3% do peso corporal e 46,7% dos sujeitos apresentaram níveis de desidratação superiores a essa média. Os resultados sugerem que a exposição ao estresse térmico e a relação volume X intensidadedo treinamento estão inadequadas, provocando uma acentuada velocidade de perda hídrica nos alunos do curso.

The aim of the present study was to evaluate hydration levels in the Basic Parachutist Course (BPC - the main program for Brazilian military parachutists training) students according to their body mass and total body water variations. To this end, a bio-impedance method was used in order to assess the subject?s fat percents. The data were collected during the 3 weeks of the first phase of the training course, January 7 - 25, 2008. The sample was randomly selected from the 422 volunteers who started the course. 90 male subjects participated in the study, and they can be characterized by the following anthropometric data: age (25.08 ± 3.96 years); weight (76.53 ± 7.39 kg); height (174.53 ± 5.85 cm) and fat percent (14.07 ± 4.09). The water loss average was 3% of the body weight and 46.7% of the subjects had higher levels of dehydration than the average. The results suggest that the course stress levels are not adequate, implying in an excessive water loss by its subjects.